The present invention relates to a system for controlling the operation of one or more interruptable electrical loads. The purpose of the demand controller of this invention is to maintain the total electrical power demand of the load at or below a predetermined peak demand. The concepts of this invention may be used for controlling a single interruptable electrical load but are preferably employed in controlling a plurality of interruptable electrical loads on a priority basis.
An electrical power demand is metered usually on the basis of a predetermined demand interval which may be, for example, a 15 minute, 30 minute or 60 minute demand interval. During this demand interval the consumption of electrical energy is accumulated and averaged. In addition to kilowatt-hour usage the customer is assessed a substantial additional charge based on the maximum value of this average during one or more billing periods. Thus, in the past systems have been devised for maintaining the demand below a predetermined peak value during the demand interval thereby limiting this peak demand charge. Some of these techniques, however, such as a zero-order constant rate comparison technique had not been totally satisfactory.
Accordingly, one object of the present invention is to provide a demand controller having an improved forecasting technique.
Another object of the present invention is to provide a demand control technique that can be implemented relatively simply without the need for excessive complex data processing and logic circuitry.